CN110434162B

CN110434162B - Method for repairing cadmium-polluted soil by using salix integra

Info

Publication number: CN110434162B
Application number: CN201910830619.8A
Authority: CN
Inventors: 诸葛玉平; 尹泽润; 娄燕宏; 晁赢; 尚晓阳; 王会; 潘红; 杨全刚
Original assignee: Shandong Agricultural University
Current assignee: Shandong Agricultural University
Priority date: 2019-09-04
Filing date: 2019-09-04
Publication date: 2020-09-15
Anticipated expiration: 2039-09-04
Also published as: CN110434162A

Abstract

The invention discloses a method for restoring cadmium-polluted soil by utilizing salix integra, which utilizes the growth characteristics of salix integra and folium isatidis that the growth rate is high and the salix integra is harvested for a plurality of years after cuttage for one year, promotes the cuttage propagation and root system building of salix integra in cadmium-polluted soil and improves the cadmium transportation and enrichment capacity of salix integra by a mode of synergistic application of adding activated carbon and spraying spermidine in soil, thereby realizing the ecological restoration of the cadmium-polluted soil. The influence of the two treatments of the activated carbon and the spermidine on the salix integra under the cadmium stress is determined, and the effect of the spermidine on enhancing the cadmium resistance of the salix integra and adsorbing and fixing soil cadmium by the activated carbon is proved. The harvested salix integra wickers can be used as wicker materials, and certain economic benefits can be created while ecological benefits are achieved.

Description

Method for repairing cadmium-polluted soil by using salix integra

Technical Field

The invention relates to the technical field of soil remediation, in particular to a method for remediating cadmium-contaminated soil by using salix integra.

Background

With the development of industry and the modernization of agriculture, the heavy metal pollution of soil becomes a serious environmental problem facing the world. According to statistics, the cultivated land area polluted by heavy metal in China reaches 10 percent, about 1.5 hundred million acres, the grain polluted by heavy metal reaches 1200 million tons every year, and the direct economic loss exceeds 200 hundred million yuan. Cadmium is a common toxic heavy metal in soil and mainly comes from automobile exhaust, mining and smelting of mining industry, overapplication of pesticides and chemical fertilizers and the like. Cadmium is one of heavy metal elements with the strongest biological toxicity, although cadmium is not an essential element for plants, cadmium is easily absorbed by plants due to certain similarity of cadmium and a plurality of divalent metal ions such as zinc, iron, calcium and the like, and once the cadmium enters the plants, the cadmium can replace active centers of a plurality of enzymes or be combined with sulfydryl in protein, so that the structure of biomacromolecules is changed, enzyme systems in the plants are damaged, the growth of the plants is harmed, and the health of human beings is seriously threatened. For example, eating cadmium-contaminated "cadmium rice" for a long period of time can cause bone pain, cause hypertension, and affect the body's enzymatic system and fertility. Similarly, excessive cadmium in soil not only has serious influence on plant growth, but also can be accumulated in crops or animals through biological enrichment, thereby bringing great threat to human health.

Phytoremediation is a remediation mode which is gradually developed and applied from bioremediation in recent years and is used for adsorbing, transferring and removing specific heavy metal pollution elements in soil by using green plants. Phytoremediation can effectively reduce or eliminate the harm of heavy metal pollution of soil (sealing function, etc., 2008). Currently, plants applied to soil heavy metal pollution remediation are divided into two types: (1) hyper-enriching plants; (2) high biomass plants having strong tolerance to heavy metal contamination and high enrichment characteristics and growing rapidly. However, the currently found super-enriched plants are mainly annual herbaceous plants, and the biomass is small. Meanwhile, the current hyperaccumulator restoration technology mainly realizes ecological benefits for soil pollution restoration and is difficult to create economic value. Therefore, the search for cadmium-contaminated soil phytoremediation materials with both ecological and economic benefits is a current research hotspot. Wherein, osier (Salix integra) The willow-willow shrub is an important raw material of willow-woven fabrics, is commonly called white willow twigs or willow twigs, has the advantages of strong adaptability, easiness in propagation, rapid growth and the like, is widely cultivated in China, and has important economic value. The variety is more, and the better variety comprises one pen, scarlet head, dyers woad leaf, willow twigs and the like, and the common characteristics of the variety are that the germination regeneration capacity is very strong, the yield is high, the willow twigs are flexible, the root system is developed, and the variety is a good tree variety for preventing wind, fixing sand, protecting slope, fixing dike and preventing water and soil loss.

Therefore, the potential of the salix integra for repairing the cadmium-polluted soil is discussed, and the method has important significance for enriching the plant types for phytoremediation. However, under the cadmium stress, the growth of the salix integra is inhibited by cadmium, so that the repair effect of the salix integra is influenced, and meanwhile, as a plant depending on cuttage propagation, the establishment of a root system of the salix integra is an important factor influencing the cuttage survival of the salix integra. Therefore, the research on how to enhance the establishment and configuration of the root system of the salix integra seedlings after cuttage and enhance the tolerance and enrichment characteristics of the salix integra to cadmium stress has important significance for excavating the potential of the salix integra in repairing cadmium-contaminated soil. At present, most of the salix integra varieties used for repairing the heavy metal contaminated soil are Weishan lake, Yibi and Dahongtou, and a method for repairing the heavy metal contaminated soil by using folium isatidis is not reported.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for repairing cadmium-polluted soil by using salix integra and folium isatidis. The method has the advantages that the soil is repaired, the economic benefit is created, the harvesting for many years after cuttage for one year is realized, the cuttage propagation and the root system building of the salix integra in the cadmium-polluted soil are promoted, the cadmium transportation and enrichment capacity of the salix integra is improved through the synergistic application mode of adding the activated carbon into the soil and spraying the spermidine, and therefore the problem that the soil is polluted by heavy metal is effectively solved.

The invention is realized by the following technical scheme:

the invention provides a method for repairing cadmium-polluted soil by using salix integra, which comprises the following steps:

(1) adding 2.5-2.8 t/hm into cadmium contaminated soil to be repaired²Activated carbon; leveling and ploughing cadmium-polluted soil and applying fertilizer;

(2) preparing cutting strips from 3 late ten days to 4 middle ten days; cutting in the soil treated in the step (1), wherein the row spacing is 15-25 cm, the plant spacing is 3-8 cm, and the cutting depth is 70-80% of the cutting strips;

(3) after the tender leaves of the willows cut in the step (2) grow, 0.8 mmol.L is prepared^-1The spermidine solution is sprayed on the leaves for 6-8 days, and is sprayed once a day, wherein the spraying amount is 4500L-5500L/hm²。

Preferably, in the step (1), the addition amount of the activated carbon is 2.65t/hm²(ii) a The active carbon is coal powdery active carbon.

Preferably, in the step (1), the fertilizer is organic fertilizer and diammonium phosphate; the addition amount of the organic fertilizer is 60-75 t/hm²(ii) a The addition amount of the diammonium phosphate is 450-600 kg/hm²。

Preferably, in the step (2), the variety of the salix integra subjected to cuttage is folium isatidis.

Preferably, the preparation method of the skewer comprises the following steps: cutting the wicker at the top end of the salix integra, removing tender buds at the top end, cutting the wicker into a flat opening, cutting the lower end of the wicker into a horseshoe-shaped inclined opening, soaking the lower end of the cut wicker in water for 2-3 days, and changing water every day; before cuttage, the willow twigs are soaked in the rooting powder solution for 12-24 hours.

Preferably, the length of the wicker at the top end of the salix integra is 15-20 cm; the length of the top tender bud is 1-3 cm;

preferably, the length of the horseshoe-shaped inclined opening is 1-2 cm, and the inclination angle of the horseshoe-shaped inclined opening is 40-50 degrees.

Preferably, the rooting powder solution is prepared by mixing ABT rooting powder and water; the concentration of the rooting powder solution is 40-60 mg.Kg^-1；

More preferably, the concentration of the rooting powder solution is 50 mg.Kg^-1。

Preferably, in the step (3), the length of the tender leaves is 2-3 cm.

Preferably, the method further comprises the steps of cutting off the wickers along the upper part of the ground by 5-10 cm after the wickers grow to be mature, and continuously watering and fertilizing the rest parts until the wickers are harvested next time; and (3) separating the xylem of the harvested salix integra from the epidermis, recovering and extracting cadmium from the epidermis and leaves, and recovering and extracting cadmium from root systems after soil remediation is finished, wherein the xylem is used as a wicker material for artwork weaving.

The invention has the beneficial effects that:

(1) by adopting the method, the salix integra for repairing the cadmium-polluted soil can be cut for a plurality of years by cuttage one year, and manpower and material resources for planting every year are saved;

(2) after the salix integra is harvested, the salix integra can be used for weaving artware, so that the method has great economic value;

(3) the salix integra is promoted to restore the cadmium-polluted soil by applying the synergistic effect of the activated carbon and the spermidine, and the effect is obvious.

Drawings

FIG. 1 shows cadmium distribution in organs of salix integra treated differently in various stages under cadmium stress.

Detailed Description

In order to clearly illustrate the technical features of the present solution, the present solution is illustrated by the following embodiments and experimental examples. The test materials used in the examples and test examples, which are not specifically described, are conventional in the art and commercially available.

Example 1:

(1) land preparation and fertilization: the ground to be repaired is ploughed flatly, and 2.65t/hm of active carbon is added into the soil before ploughing the soil². Ploughing to a depth of 20cm, and applying organic fertilizer at 60t/hm²600kg/hm of diammonium phosphate²。

(2) Carrying out cuttage: shearing 17cm of willow twigs at the top end of folium Isatidis, removing 2cm of tender shoots at the top, shearing into flat mouth, shearing the lower ends of the willow twigs into 40-degree horseshoe-shaped oblique mouths with length of 2cm, soaking the lower ends of the willow twigs of Salix integra in water for 2 days, and changing water every day. Soaking in 50 mg/kg before cutting^-1The rooting powder solution of (1) for 16 hours. And (3) cutting in soil, keeping the row spacing of 20cm and the plant spacing of 5cm, keeping the cutting depth of 70% of the wicker, and thoroughly watering during cutting to ensure sufficient root water of the salix integra.

(3) Field management: after the willow seedlings are planted, attention is paid to clearing weeds in the field, and watering is carried out in time according to the soil condition. After the cutting is finished and the willow branches grow tender leaves, 0.8 mmol.L is prepared^-1The spermidine solution is sprayed on the leaf surface, and the spraying amount is 4500L/hm²Spraying for 7 days.

(4) Harvesting: after the wickers grow to be mature, cutting the wickers along 5cm of the upper part of the ground, and continuously watering and fertilizing the rest part until the wickers are harvested next time; and (3) separating the xylem of the harvested salix integra from the epidermis, recovering and extracting cadmium from the epidermis and leaves, and recovering and extracting cadmium from root systems after soil remediation is finished, wherein the xylem is used as a wicker material for artwork weaving.

Example 2:

(1) land preparation and fertilization: the ground to be repaired is ploughed flatly, and before ploughing the soil, the soil is addedActivated carbon 2.65t/hm². Ploughing to a depth of 20cm, and applying organic fertilizer at 75t/hm²450kg/hm of diammonium phosphate²。

(2) Carrying out cuttage: shearing 17cm of willow twigs at the top end of folium Isatidis, removing 2cm of tender shoots at the top, shearing into flat mouth, shearing the lower ends of the willow twigs into 50-degree horseshoe-shaped oblique mouths with length of 2cm, soaking the sheared lower ends of Salix integra twigs in water for 3 days, and changing water every day. Soaking in 50 mg/kg before cutting^-1The rooting powder solution of (1) for 24 hours. And (3) cutting in soil, keeping the row spacing of 20cm and the plant spacing of 5cm, keeping the cutting depth of 75% of the willow twigs, and thoroughly watering during cutting to ensure sufficient root water of the salix integra.

(4) Harvesting: after the wickers grow to be mature, cutting the wickers along 10cm of the upper part of the ground, and continuously watering and fertilizing the rest part until the wickers are harvested next time; and (3) separating the xylem of the harvested salix integra from the epidermis, recovering and extracting cadmium from the epidermis and leaves, and recovering and extracting cadmium from root systems after soil remediation is finished, wherein the xylem is used as a wicker material for artwork weaving.

Test examples

1) Location and time of experiment

The soil to be tested is brown soil which is taken from resource and environment college laboratory of Shandong university of agriculture, the pH value (water-soil ratio 2.5:1) of the soil is 7.45, and the organic matter content is 19.42 g.kg^-11.08 g/kg of total nitrogen^-192.37 mg/kg of alkaline hydrolysis nitrogen^-135.85 mg/kg of available phosphorus^-1Quick-acting potassium 109.71 mg/kg^-1Cadmium content 0.15 mg/kg^-1. By addition of CdCl₂(analytically pure) simulating soil cadmium pollution, and enabling soil Cd to be in accordance with early-stage preliminary test results²⁺The concentration is 24.50 mg/kg^-1And mixed well and used for testing after balancing for 14 days.

2) Design of experiments

Adopting a pot experiment, independently using activated carbon and spermidine, cooperatively using spermidine and activated carbon, wherein the application amount of spermidine and activated carbon is shown in table 1, fully and uniformly mixing the activated carbon and soil, selecting salix integra seedlings with consistent growth vigor, planting the salix integra seedlings into pots, spraying 5 mL of spermidine solution to each salix integra every day, continuously spraying 7 days, spraying clear water in a contrast treatment manner, continuously watering every day after the treatment is finished to ensure the growth of the salix integra, culturing for 90 days, taking out plants and soil samples for detection at 30 days, 60 days and 90 days respectively, collecting soil attached to root systems, cleaning the root systems of the plants, soaking the plants in 20 mmol.L, and soaking the plants in the soil^-1Washing with EDTA Na solution for 30 min with double distilled water to remove Cd attached to the surface of the root system²⁺The washed sample is used for detecting various indexes such as biomass. And after the soil collected on the root system is air-dried, grinding the soil through a 0.23 mm sieve, and measuring the content of Cd in the soil.

Description of the amount of activated carbon: the addition amount of the active carbon in the field test of the invention is 2.65t/hm²The plowing depth is generally 20cm when the salix integra and indigowoad leaf are planted in the field, and the average volume weight of the soil is 2.65g/cm³(ii) a The addition amount of the activated carbon in each kilogram of soil is calculated to be 0.5g, namely the addition concentration of the activated carbon in the soil is 0.5 g/Kg. In order to facilitate the test and obtain reasonable test data, the invention selects a pot experiment. Because the area of the potted soil is very small, if the active carbon is 2.65t/hm²The amount of the fertilizer is added into the potting soil, so that the amount is not practical and is not convenient to calculate. Therefore, the weight of the potted soil is weighed, and the activated carbon is added according to the adding concentration of the activated carbon in the soil of 0.5 g/Kg.

TABLE 1 application rates of spermidine and activated carbon

3) The detection method comprises the following steps:

A) determination of biomass and relative growth rate:

the whole plant was weighed before the start of treatment and after the end of treatment to obtain the starting and ending biomass, and the relative growth rate was calculated. After the treatment is finished and the whole plant is weighed, the plant is respectively weighed according to xylem, epidermis, leaves and root system to obtain the biomass of each part.

B) And (3) measuring the root system configuration:

put into root system scanner Epson V700's glass groove to the root system, pour into the deep deionized water of 1 cm and make the root system fully disperse, use tweezers adjustment to disperse for avoiding the root system to overlap alternately when necessary, the scanning obtains the image, carries out the analysis in leading-in WinRHIIZO root system analytic system of image.

C) Measurement of physiological indices:

accurately weighing 0.1 g of leaves (roots) and placing the leaves (roots) in a mortar subjected to precooling treatment, grinding the leaves with liquid nitrogen, adding 0.9 mL of physiological saline, transferring the mixture into a centrifuge tube, centrifuging the mixture at 4 ℃ for 10 min, and collecting supernatant for measuring physiological indexes.

H₂O₂Content determination: detecting by using a hydrogen peroxide detection kit (A064-1);

and (3) measuring the content of GSH: detecting by using a glutathione detection kit (A006-1);

determination of superoxide anion generating activity units: detecting by using an anti-superoxide anion detection kit (A052);

SOD activity determination: detection was carried out using a superoxide dismutase test kit (A001-2).

All the kits are purchased from a bioengineering institute built in Nanjing, China, and all the operations are strictly carried out according to the kit instructions.

D) Determination of relevant test parameters for cadmium:

deactivating enzyme at 105 deg.C for 30 min, oven drying at 80 deg.C to constant weight, grinding, and sieving. Dried samples (root 0.1 g, leaf 0.2 g, skin 0.2 g, xylem 0.2 g) were weighed out separately and placed in a graphite crucible to be ashed at 490 ℃ for 50 min. The ashed material was added with 15 mL of mixed acid (V (HClO)₄):V(HNO₃) And =1: 4), transferring the mixture to a digestion tube for digestion until the mixture is clear, and metering the volume to a 50 mL volumetric flask for measurement.

And digesting the soil sample by adopting a wet method. Accurately weighing 0.2-0.5 g of a sample in a 50 mL polytetrafluoroethylene crucible, wetting with a small amount of water, adding 10 mL of hydrochloric acid, and standing overnight for cold digestion. Heating on a hot plate at 130 deg.C for 1 h. And after the soil is initially decomposed, taking down the soil to be slightly cooled, adding 5 mL of nitric acid and 5 mL of perchloric acid, putting the soil on an electric hot plate for continuous heating, adding 3 mL of hydrofluoric acid after 15 minutes, covering the electric hot plate at 220-260 ℃, heating for about 1 hour, and opening the cover. Heating until dense white smoke is emitted, and covering to decompose the black organic carbide. After the black organic carbide is decomposed, the cover is opened, the acid is driven to reduce the white smoke, and the cup is filled with transparent flowable paste. Taking down the crucible and the inner wall of the crucible to be slightly cooled, washing the crucible and the inner wall of the crucible by double distilled water, adding 1 mL of nitric acid, and warming by using the residual temperature until the nitric acid is volatilized completely. And (4) taking down and cooling, transferring the solution into a 50 mL volumetric flask, adding water to a constant volume, slowly filtering by quantitative filter paper, and transferring to a centrifugal tube to be tested. The cadmium concentration in the solution is measured by an atomic absorption instrument, and the cadmium concentration, the cadmium content, the cadmium enrichment total amount, the removal rate, the transfer coefficient and the enrichment coefficient of each organ are calculated.

Removal rate (%) = Cd content enriched by plant absorption/Cd content in nutrient solution (soil) before treatment × 100%;

the enrichment coefficient = concentration of Cd enriched in the plant/concentration of Cd in the nutrient solution (soil);

transfer coefficient = Cd concentration in the overground part of the plant/Cd concentration in the underground part of the plant.

4) Analysis of results

I) Effect of treatment on growth of Salix integra

As can be seen from the biomass of the salix integra at different periods (Table 2), the treatment by independently adding Activated Carbon (AC) and Spermidine (SP) is obviously greater than the control treatment (CK), and the effect of the AC treatment is better than that of the SP treatment, so that the cadmium stress on the salix integra is relieved, and the growth promotion effect of the salix integra is more influenced by the activated carbon. Meanwhile, activated carbon and spermidine are added for synergistic treatment (CS), the biomass of the salix integra is greater than CK, AC and SP in different periods, and therefore cadmium stress on growth of the salix integra is relieved, and CS treatment has a better relieving effect.

TABLE 2 Salix integra biomass treated at different times

Ii) response of Salix integra organs to different treatments

TABLE 3 treatment of biomass of organs of salix integra at different times

As can be seen from Table 3, under the synergistic effect of activated carbon and spermidine, the biomass of different organs of salix integra is highest in terms of leaves and root systems, and the leaves are slightly higher than the root systems. According to the biomass in different periods, the CS treatment is higher than the CK treatment, the SP treatment and the AC treatment, and the CS treatment can promote the growth of each organ of the salix integra for relieving the cadmium stress on the salix integra.

Iii) influence of different treatments on root system configuration of salix integra under cadmium stress

TABLE 4 root configuration of salix integra treated differently at each stage

As can be seen from Table 4, all the root system configuration indexes were raised by the synergistic effect of activated carbon and spermidine at each period. At 30d, the fractal dimension, the number of nodes and the number of branches under the AC processing are greater than those of SP processing; at 60d, the fractal dimension, the connection number and the node number of the AC processing are greater than those of the SP processing; when 90d is reached, only the fractal dimension and the connection number of the AC processing are greater than those of the SP processing, and the number of nodes, the number of root tips, the number of branches and the number of crossings are less than those of the SP processing. Therefore, the AC treatment has better effect on promoting the root system configuration of the salix integra than the SP treatment. And the CS treatment is obviously larger than the AC and SP treatments in each period, which shows that the CS treatment is more favorable for the growth and development of the root system of the salix integra.

Iv) Effect of different treatments on physiological Activity of Salix integra under cadmium stress

As can be seen from Table 5, the AC and SP treatments significantly reduced H in the Salix integra leaves at 30d and 60d₂O₂The content, at 90d, of the AC and SP treatments was not significantly different from the CK control, but the CS treatment was alwaysSignificantly lower than the CK control; meanwhile, the glutathione content in the salix integra leaves is remarkably improved by AC and SP treatment at 30d and 60d, but the SP treatment is remarkably larger than that of AC and CK control at 90d, the AC treatment is not remarkably different from that of CK control, and the CS treatment is remarkably larger than that of CK at 30d, 60d and 90 d; the superoxide anion generating activity units of the CS and SP treatments are also induced to be significantly reduced, but the AC treatment has no significant difference with CK at 30d and is lower than CK at 60 and 90 d; at 30d and 90d, the superoxide dismutase activity of the CS and SP treatments is obviously higher than that of the CK, but the AC treatment and the CK have no obvious difference all the time. The data show that CS treatment has the best effect on physiological activity of salix integra under cadmium stress.

TABLE 5 physiological Activity of Salix integra treated at different periods

V) influence of different measures on soil cadmium pollution remediation

The remediation capability of salix integra on cadmium-contaminated soil is remarkably enhanced through synergistic treatment, the transfer coefficient and the removal rate (shown in table 5) in each period are remarkably increased, and the transfer coefficients are respectively improved by 43.48% (30d), 106.12% (60d) and 141.07% (90 d); the enrichment coefficient of cadmium of the salix integra treated by CS is larger than that of CK contrast at 30d and 60 d; at 90d, the removal rate of the CS treatment reached the highest level (4.10%).

TABLE 6 enrichment characteristics of salix integra treated at different times

Test results show that the biomass of salix integra under synergistic treatment is further improved compared with spermidine treatment and activated carbon treatment, the biomass of salix integra under cadmium stress can be increased by both activated carbon and spermidine, and the action mechanism of activated carbon lies in fixing Cd in soil²⁺Thereby reducing cadmium stress on the salix integra and increasing the biomass of the salix integra; when two substances are used simultaneously, the activated carbon is directly added into the soil before treatment, and the Cd in the soil is firstly adsorbed²⁺The cadmium concentration of soil in the environment of the salix integra is reduced, so the salix integra is appliedThe effect of spermine on improving the biomass of salix integra and promoting the root system configuration is reduced. Although the enrichment coefficient, the transport coefficient and the removal rate are higher under the condition of singly using spermidine, the cutting survival and the growth development of the salix integra are reduced due to the inhibition effect of cadmium stress on the plant growth, the repairing effect of spermidine treatment is influenced, the wide application of the salix integra in repairing cadmium-contaminated soil is not facilitated, the removal rate of synergistic treatment after 60 days is always the highest, on one hand, the growth and the development of the salix integra are effectively promoted due to the inducing effect of spermidine on the physiological activity of the salix integra, on the other hand, the cutting survival biomass of the salix integra is improved, and the repairing effect of the salix integra on the cadmium-contaminated soil is promoted. In conclusion, the synergistic treatment is more beneficial to the remediation of the cadmium-polluted soil.

Of course, the above description is not limited to the above examples, and the undescribed technical features of the present invention can be implemented by or using the prior art, and will not be described herein again; the above embodiments and drawings are only for illustrating the technical solutions of the present invention and not for limiting the present invention, and the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that changes, modifications, additions or substitutions within the spirit and scope of the present invention may be made by those skilled in the art without departing from the spirit of the present invention, and shall also fall within the scope of the claims of the present invention.

Claims

1. A method for repairing cadmium-polluted soil by using salix integra is characterized by comprising the following steps:

adding 2.5-2.8 t/hm into cadmium contaminated soil to be repaired²Activated carbon; the active carbon is coal powdery active carbon; leveling and ploughing cadmium-polluted soil and applying fertilizer; the fertilizer is organic fertilizer and diammonium phosphate; the addition amount of the organic fertilizer is 60-75 t/hm²(ii) a The addition amount of the diammonium phosphate is 450-600 kg/hm²；

(2) Preparing cutting strips from 3 late ten days to 4 middle ten days; cutting in the soil treated in the step (1), wherein the row spacing is 15-25 cm, the plant spacing is 3-8 cm, and the cutting depth is 70-80% of the cutting strips; the salix integra variety subjected to cuttage is folium isatidis;

(3) after the willow branches cut in the step (2) grow tender leaves, 0.8mmol/L spermidine solution is prepared for spraying on the leaf surfaces, the spraying time is 6-8 days, the spraying is carried out once a day, and the spraying amount is 4500-5500L/hm²。

2. The method according to claim 1, wherein in step (2), the skewer preparation method is: cutting the wicker at the top end of the salix integra, removing tender buds at the top end, cutting the wicker into a flat opening, cutting the lower end of the wicker into a horseshoe-shaped inclined opening, soaking the lower end of the cut wicker in water for 2-3 days, and changing water every day; before cuttage, the willow twigs are soaked in the rooting powder solution for 12-24 hours.

3. The method of claim 2, wherein the salix integra top wickers are 15-20 cm in length; the top tender shoots are 1-3 cm in length.

4. The method as claimed in claim 2, wherein the length of the horseshoe-shaped bezel is 1-2 cm, and the inclination angle of the horseshoe-shaped bezel is 40-50 °.

5. The method of claim 2, wherein the rooting powder solution is ABT rooting powder mixed with water; the concentration of the rooting powder solution is 40-60 mg/Kg.

6. The method as claimed in claim 1, wherein in the step (3), the length of the young leaves is 2-3 cm.

7. The method of claim 1, further comprising: after the wickers grow to be mature, cutting off the wickers along the upper part of the ground by 5-10 cm, and continuously watering and fertilizing the rest part until harvesting next time; separating the xylem of the harvested salix integra from the epidermis, and recovering and extracting cadmium from the epidermis and leaves;

or after the soil is repaired, cadmium is recovered and extracted from root parts of the salix integra, and xylem is used as a wicker material for artwork weaving.